Most masonry chimneys are constructed with an inadequate cap made from which material?

Masonry chimneys are often constructed with caps made from mortar mix that is not adequately designed to withstand the effects of weather and thermal expansion. Over time, mortar can deteriorate, leading to issues such as cracking and water infiltration. This is a problem because a chimney cap needs to be durable and capable of directing water away from the chimney structure to prevent damage.

Using mortar mix as a cap limits its effectiveness in these areas. In contrast, materials like brick, concrete, and even metal are more suitable for chimney caps as they provide better durability, water resistance, and structural support. Concrete, for instance, can be cast into solid caps that effectively shield the chimney from the elements.

A wooden cap would be unsuitable due to its susceptibility to rot and damage from exposure to moisture. Therefore, the inadequacy of mortar mix in this context highlights why it is an inappropriate choice for chimney caps.